Spinal surgery distractor with an integrated retractor

ABSTRACT

A tool for use in spinal surgery includes a combined retractor and distractor. The retractor includes a slotted keyway wherein a keyed portion of a spinal distractor is engagable therewith. This retractor and distractor combination slide together to displace a portion of the intervertebral disk space to restore or maintain intervertebral spacing and facilitate retraction of surrounding soft tissues while disk space surgery is performed. The distractor head and mating portion of the retractor have matching profiles that enable the retractor to maintain distraction of the vertebra after removal of the distractor portion of the tool, permitting access to increase at the operating site. The retractor has convex curved surfaces that interface with a majority of retracted soft tissues during progression of the retraction process, which enhance retractor safety.

FIELD OF INVENTION

This invention generally relates to the field of surgical appliances fordisk space spinal surgery, specifically retractors and distractors thatare used to facilitate retraction of soft tissue surrounding the discspace, and the management intervertebral spacing in disc space surgerywith a distraction device.

BACKGROUND OF THE INVENTION AND PRIOR ART

Surgery involving spinal disc space operations that require open accessthrough an incision usually necessitate a means to hold the incisionopen without injury to retracted tissue while the surgeon operates onthe diseased or injured portion of the spine. This retraction reducesthe required size of the surgical incision, contributing to improvedvisualization of pathology, while decreasing surgical risk factors. Inaddition to this, disc space surgical procedures often require a meansto stabilize and maintain intervertebral spacing via a distractiondevice for the disc space being operated on.

Few retractors used in disk space surgery incorporate a distractiondevice to maintain intervertebral spacing. Those that do, incorporate adistractor that is usually cumbersome, and bulky and often requiresdrilling. One example of a device of similar function is theretractor-distractor device within U.S. Pat. No. 5,944,658. Like thisexample, most spinal retractors for open access surgery that incorporatea distractor are typically complex, awkward, time consuming to set up,and are usually comparatively difficult work with when there is a needto quickly modify apparatus position, distraction within new position,and degree of retraction, when compared to dedicated devices.

SUMMARY OF THE INVENTION

The present invention is broadly directed toward a spinal distractorthat is combined with a retractor, for use in lumbar, thoracic, andcervical disc space surgery. At this time, the preferred usage of theinvention involves lumbar spine surgical procedures of the disk spaceand vertebral distraction at the L5-S1, L4-L5, L3-L4, and L2-L3 levelsvia a retroperitoneal approach anteriorly with retraction of adjacentsoft tissue.

The present invention consists of two major parts of an integratedassembly that is used as a spinal surgery retractor and distractor. Thedistractor portion of the invention has a distractor head or plugincorporating a keyed shape on its face that mates to a portion of theretractor via a keyway in the distal end of the retractor. This matingportion of the retractor has a profile that matches or is similar to theprofile of the distractor head. The distractor head has a rod fastenedto it, preferably using machine screw threads that provide a means toapply insertion force to the entire assembly, and removal force to thedistractor portion of the assembly.

Once the distractor is engaged with the retractor through its keyway,the shape of the retractor keyway does not allow the distractor to slideahead of the retractor. This enables the distractor to apply insertionforce to the entire assembly to enable progression into the incision,followed by insertion of the distal tip of the entire assembly into aportion of the disc space, with most or all of the insertion forceapplied to the distractor.

A slot adjacent to the retractor keyway enables removal of thedistractor from the retractor after insertion of the assembly into theoperating site, allowing for an increase of exposure in the operatingfield, and for minute changes in distraction by exchanging thedistraction portion of the assembly. After the assembled distractor andretractor are inserted into the operating site, the retractor can beused to maintain distraction at the operating site by employing itsdistal end profile (described above).

The retractor has a thinned or blade shaped distal end to allow forflexibility of its distal portion, enabling further progression ofretraction and permitting increased access to the operating field. Inaddition, the retractor has convex curved surfaces that interface with asignificant amount of retracted soft tissue during progression of theretraction process, which contributes towards retractor safety. Theportion of the retractor tool described above as “thinned or bladeshaped”, is formed at the opened end of the above-described slot byabruptly tapering to a uniform thickness which extends uniformly to theproximal edge of the surgical tool.

In summary, when the preferred embodiment of the invention is utilized,it provides for the complete removal of the disk, removal of thevertebral cartilaginous end-plates in a safe fashion—protecting the softtissue surrounding the disk, as well as maintaining distraction of thedisk space, allowing one to do the most complete removal of the diskspace and fragments that have herniated behind the vertebral body.

Accordingly it is an objective of the instant invention to enable thedirect placement of a retractor attached to a distractor to maintainsoft tissue distraction without the need for an individual holding theretractor blade and maintaining pressure on the soft tissues. Thisprovides the surgeon with enhanced control of the soft tissue retractionprocess, thereby reducing the chances of necrosis of the soft tissue.

It is yet a further objective of the instant invention to employ adistractor retractor assembly which reduces the chances of soft tissuecoming out from underneath the retractor due to the fact that a portionof the retractor extends down into the disk space. This is particularlyimportant, as once portions of the vertebral disk have been removed, theresulting void presents a space for soft tissue such as blood vesselsand nerves to enter, increasing the chances for soft tissue damageduring final removal of disk space material and/or placement ofimplants, i.e., total disk replacements or vertebral interbody fusions.

It is yet another objective of the instant invention to have a retractorwhich has a distal flexible portion, allowing one to bend this portionof the retractor away from the operating field, resulting in an increaseof the amount of exposure and light that can be brought into theoperating field, improving the quality of the exposure. Everything thatcan be done to improve the quality of operating field exposure with lessrisk to the soft tissue minimizes the overall risks of the surgery.

It is still yet another objective of the instant invention to integratethe distractor head with the retractor allows for maintenance of thedisk height during removal of the disk material, which tends to collapseas the disk material is removed. This is possible since successivereplacement of the distraction portion of the assembly is enabled viathe keyway and slot on the retractor. This characteristic of theinvention aids in the gradual progression of distraction. Thus,providing control of distraction while giving a much bettervisualization of the soft tissue within the disk as well as improvingaccess for the removal of any disk herniated fragments from behind thedisk space.

It is still yet another objective of the instant invention to provide adevice whereby surgical distraction of vertebra and retraction ofadjacent soft tissue can be maintained by the retractor after thedistractor integrated with its retractor has accomplished initialdistraction. Thus allowing subsequent removal of the distractor toolfrom the retractor keyway and the operating site after the initialdistraction. This provides retraction with a comparative increase inaccess to the operating site when distraction and retraction arecoincident surgical requirements. This can be followed with incrementaldistraction changes by exchanging the distractor portion of the assemblyand/or alternately changing distractor-retractor assemblies laterally.

Other objectives and advantages if this invention will become apparentfrom the following description taken in conjunction with any drawingswherein are set forth, by way of example, certain embodiments of thisinvention. Any drawings contained herein constitute a part of thisspecification and include exemplary embodiments of the present inventionand illustrate various objects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the distractor tool combined with the retractor, with thelengthwise edge of the retractor exposed;

FIG. 2 shows the retractor without its distractor, with the keyway,matching profile and slot adjacent to the keyway exposed with referencenumber 10;

FIG. 3 shows the retractor with corresponding reference numerals;

FIG. 4 shows an orthogonal top view of the retractor with hidden linesillustrating the extent of the distal end keyway and portions of thesoft-tissue-interfacing convex surfaces;

FIG. 5 is a cross sectional view along 5-5 in FIG. 4 of the distal tipof the retractor, showing one orthogonal view pointing into theretractor keyway;

FIG. 6 is a cross sectional view along 6-6 in FIG. 4 of the distalportion of convex surfaces on the retractor and orthogonal view pointinginto the slot that is adjacent to the keyway;

FIG. 7 is a cross sectional view along 7-7 in FIG. 4 of the middleportion of the convex surfaces on the retractor and the middle of theslot that is adjacent to the keyway;

FIG. 8 shows the distractor head and distractor rod separated, withhidden lines illustrating the extent of the keyed portion of thedistractor head and machine screw threads on the distractor rod;

FIG. 9 shows an orthogonal view of the distractor head with the matchingprofile and keyed portion facing out;

FIG. 10 shows an orthogonal view of the side of the distractor head witha side view of the keyed portion of the distractor;

FIG. 11 shows an orthogonal view of the distal end of the distractorhead;

FIG. 12 is a top view of the retractor, distractor head, and distractorrod, with the direction of placement indicated for integration; and

FIG. 13 is a side view of the of the spine with the distal tip of theretractor inserted in the disc space, with ‘V’ indicating vertebra and‘D’ indicating the intervertebral disc.

DRAWINGS Reference Numerals

Description of elements 1-12. 1 retractor; 2 distractor head; 3distractor rod; 4 retractor distal tip; 5 flexible section of retractor;6 taper to flexible section; retractor convex curves; 8 retractorkeyway; 9 starting point of retractor matching-profile; 10 slot adjacentto keyway; 11 keyed portion of the distractor head; and 12 endpoint-matching profile.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the present invention with all its partsintegrated is illustrated in FIG. 1. Within this figure the retractor 1is shown with the distractor head 2 engaged with the distal tip of theretractor 4 (shown in proportion with a 14 mm wide distal tip). Thedistractor head 2 is fastened together with distractor rod 3 withmachine screw threads. With the distractor portion of the assemblyremoved as shown in FIG. 2, the slot 10 of the retractor portion of theinvention that enables removal of the distractor head is visible.

Similarly, FIG. 3 details other features of the retractor that arevisible when the distractor portion of the assembly is removed. Thedetail shown in FIG. 3 illustrates the distal tip of the retractor,which has a profile that matches the profile of the distractor head, andis indicated as feature reference 4 (shown in proportion with a 14 mmwide profile). This feature incorporates the retractor keyway 8, whichtogether with the keyed portion 11, forms a dovetail joint to secure thedistractor head 2 to the retractor distal tip 4 on the face that mateswith the distractor head 2 {shown in FIG. 1}. The keyway 8 extends andopens to the slot 10 shown on FIG. 2.

Continuing further from the distal tip and on the broad side opposite ofthe slot 10 (FIG. 2) of the retractor as shown in FIG. 3, is a featurereferenced as 7, which shows the convex surfaces that interface withsoft tissue. In FIG. 3 shown, indicated by feature reference number 6 isan abrupt taper. This taper ends at the feature referenced as 5,resulting in a usable flexibility of the proximal portion that is shownas feature 5 within FIG. 3. Feature 5 has been previously described inthe summary as ‘thinned or blade shaped’ and thus, the retractor portionof the assembly can be alternately described as a retractor blade,although it is much more intricate and functional than a simple bladestructure.

FIG. 4 also illustrates a view of the retractor (retractor bladestructure) without the distractor portion of the assembly. This view ofthe retractor shows the extent of the distal tip of the retractor, whichincorporates the profile that matches the distractor head profile (FIGS.1 and 8 ref. # 2) using feature reference numbers 9 and 12 as limits.This view of the distal tip of the retractor also shows the extent ofthe hidden portion of the keyway between feature reference numbers 9 and12 (shown in proportion with a 14 mm wide distal tip profile). Inaddition, FIG. 4 also references cross sections of the retractordepicted in FIGS. 5, 6, and 7.

The illustration in FIG. 5 shows an enlarged view of the cross sectionof the distal tip of the retractor. This figure shows the crosssectional shape of the retractor keyway 8. Additionally, the keyway 8sectional view in FIG. 5 shows a beveled shape, which enables the keyway8 to retain the distractor head 2 {shown in FIG. 11 when its keyed faceis slid into the retractor keyway 8.

The cross section of the distal portion of the slot adjacent to theretractor keyway (top of illustration) and the distal convexly curvedsurfaces (bottom of illustration) that interface with soft tissue—areshown in FIG. 6. The middle cross section of the same type of surfacesis shown in FIG. 7.

An orthogonal view of the distractor head with the matching profile andkeyed section facing out is illustrated in FIG. 9. The hidden lineswithin this figure show the interface of the keyed section of thedistractor head and its matching profile, as well as an example of theextent of the distractor rod fastening hole. Also note that the distalend of the keyed section (shown in FIG. 9) is round and matches thedistal end of the retractor keyway 8. This feature creates an interface,that when slid together with the retractor keyway, prevents thedistractor from sliding in advance of the retractor. FIGS. 10 and 11 areorthogonal views from the side and distal end of the distractor headwith further detail of the keyed section.

The organization of the complete assembly is illustrated in FIG. 12. Asshown in this figure, the distractor rod 3 is fastened to the distractorhead 2 and this distractor tool assembly is slid into the retractor inthe direction indicated until the retractor keyway stops the slidingaction with its closed curved end (feature reference 8).

Operation of Invention

The operation of the invention is described in the following paragraphin part referring to the abbreviated illustration in FIG. 13, whichshows the lumbar spine and the retractor, with “D” indicatingintervertebral disks and “V” indicating lumbar vertebra. The preferredapplication of the invention is detailed as follows:

The primary surgical procedures anticipated to utilize the invention atthis time involve the lumbar spine, especially those concerningdiskectomies at the L5-S1, L4-L5, L3-L4, and L2-L3 levels via aretroperitoneal approach anteriorly with retraction (Refer to FIG. 13).In reference to the most anticipated utilization, bilateral placement ofthe retractors (blades) is suggested, with placement to be as far to oneside of the other initially as possible, after insertion of thedistractor-retractor assemblies and subsequent initial removal of thedistractors. This allows for maximal exposure to disk space whileworking on the other side.

It is preferred to initially remove some of the inner nucleus pulposusprior to insertion of the retractor/distractor assembly and initialdistraction of the disk space, thereby eliminating the risk of pushingmaterial into the spinal canal. In addition, during placement of thedistractors in the disk space, it is also part of the preferred methodto minimize the possibility of over distraction of the disk space, bydistracting in a graduated fashion rather than trying to bring the diskspace up to its maximal size immediately.

Generally, for the lumbar region, it is preferable to start out with an8 mm distractor head with matching retractor initially, and thengradually increasing to the size desired via procedurally alternatingthe removal and insertion of retractor-distractor assemblies laterally.Coincident with these procedures, one must be careful when dealing withosteoporotic bone, so that one does not over distract, since this mightcreate some risk of compression fractures or making divots in the bonewhich can make future placement of implants within the disk-spacedifficult. After the desired distraction is achieved, the distal tip ofthe retractor is left in the disk space during the remainder theoperation allowing it to maintain distraction while providing a meansfor retraction (FIG. 13).

When the desired distraction is achieved with the distractor-retractorassembly, the progression of retraction may be continued or maintainedwith the flexible portion of the retractor while distraction is beingmaintained with the matching profile of the distal tip of the retractor.

Alternative Embodiments

Anticipated revisions that are conceptual extensions of the abovedescribed preferred embodiment include, but are not limited to; anassembly that has distractor rod diameter and length changes, othermethods of fastening the distractor head to the rod, changes in thevariation of convexly curved surfaces (soft tissue interface), curvemodifications to distractor head and retractor matching profiles, andsize modifications involving differing proportions of several aspects ofthe assembly to enable use for posterior to anterior procedures from thelumbar to cervical regions of the spine. Additional possible embodimentsare listed as follows:

The thin flexible blade-like portion of the tool may be proportionallyincreased in length, while correspondingly shortening other prominentfeatures like the keyway slot and its opposing surfaces to enable betteruse in other regions of the spine.

Distractor head surfaces may be modified with rasp surfaces to enablepreparation of vertebral endplates for various implants and grafts forspinal fusion or disk replacements.

Distractor head matching profile available with differing thickness toenhance or augment other distractor head features.

Distractor head and distal tip of retractor modified to include a lightsource for better visualization of the operating field.

The shape of the retractor and/or distractor may by modified with formedor rectangular sections to accept commonly used implants and grafts forspinal fusion or disk replacement.

Retractor changes in the curvature surrounding the blade and the amountof the retractor which is solid versus flexible (thinned section).

Radio opacity to enable x-ray imaging while portions of the assembly areleft in the operating site.

Additional alternative embodiments offer marked increases in thefunction and utility of the present invention over and above the currentpreferred embodiment. This is significant, considering that the currentpreferred embodiment offers important advantages in the surgical arenasuch as:

The direct placement of a retractor attached to a distractor to maintainsoft tissue retraction without the need for an individual holding theretractor blade and maintaining pressure on the soft tissues, whichprovides the surgeon with additional control of the soft tissueretraction process.

A distractor retractor assembly that reduces the chances of soft tissuecoming out from underneath the retractor due to the fact that a portionof the retractor extends down into the disk space. This is particularlyimportant, since the migration of the soft tissue during spinal surgeryshould be minimized, since it could increase the chances for soft tissuedamage during final removal of disk space material and/or placement ofimplants.

A retractor which has a proximal flexible portion, allowing one to bendthis portion of the retractor away from the operating field, resultingin an increase of the amount of visual exposure and light that can bebrought into the operating field, resulting in improved quality of thevisual exposure at the operating site.

The integration of a distractor head with a retractor to providemaintenance of the disk height during removal of the disk material,which tends to collapse as the disk material is removed. This ispossible since successive replacement of the distraction portion of theassembly is enabled via the keyway and slot on the retractor. Thischaracteristic of the invention aids in the gradual progression ofdistraction in addition to allowing for greater visibility, thusimproving access for the removal of any disk herniated fragments frombehind the disk space.

Surgical distraction of vertebra and retraction of adjacent soft tissuecan be maintained by the retractor after the distractor integrated withits retractor has accomplished initial distraction. Thus allowingsubsequent removal of the distractor tool from the retractor keyway andthe operating site after the initial distraction, providing retractionwith a comparative increase in access to the operating site whendistraction and retraction are coincident surgical requirements.

These are not the only conceivable advantages that the currentembodiment offers, since the unique nature of the having a keyeddistractor head attached to a rod, which offers the option to beintegrated with a retractor—can offer other advantages based on emergingprocedures that may call for its use.

All patents and publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

1. A distractor retractor assembly for use in spinal surgery comprising:a distractor retractor assembly including a distractor portion and aretractor portion, said distractor portion including a distractor headand a distractor rod, said distractor head having a distal end and aproximal end, said distractor rod is removably secured to said proximalend of said distractor head, said distal end of said distractor headhaving a tapered profile between said distal end and said proximal endand being constructed and arranged for insertion between adjacentvertebral bodies, said distractor head including a plurality of sidefaces positioned between said distal end and said proximal end, a keyedshaped projection secured to one of said side faces, said retractorportion including a tapered distal tip portion, a central portion, and aproximal portion, said retractor portion being approximately the samelength as the distractor portion, said distal tip portion of saidretractor portion having a lateral dimension proximate a lateraldimension of said distractor head, said tapered distal tip portion alsobeing proximate the same shape as said distractor head, said tapereddistal tip portion being constructed and arranged for insertion betweenadjacent vertebral bodies, said retractor portion being substantiallyplanar in a single plane along a longitudinal length of said retractorportion, said central portion of said retractor portion including atleast one surface which is convex and extends upwardly with respect to alateral surface of said retractor portion, said tapered distal tipportion of said retractor portion including a keyway on a surface ofsaid tapered distal tip portion and between lateral edges of saidtapered distal tip portion, said keyed shaped projection of saiddistractor head having a profile which is constructed and arranged toengage and cooperate with said keyway to operatively connect saiddistractor portion and said retractor portion enabling insertion of saiddistractor retractor assembly between adjacent vertebral bodies, saidkeyway constructed and arranged to enable said distractor head to beremoved from said retractor portion, said retractor portion beingflexible thereby permitting it to bend sufficiently to move soft tissuewhile remaining inserted between adjacent vertebral bodies, said keyedshaped projection and said keyway forming a dovetail joint.
 2. Thedistractor retractor assembly of claim 1, wherein said keyway has aclosed shape at its distal end; whereby said closed shape prevents saidkeyed distractor head from sliding in advance of said retractor portionwhen both said distractor portion and said distractor portion togetherare inserted into an operating site.
 3. The distractor retractorassembly of claim 1, wherein said distractor rod enables an insertionforce to be applied to said distractor head and thereby an insertionforce is applied to said retractor through said keyway.
 4. Thedistractor retractor assembly of claim 1, wherein said keyway preventssaid distractor head from separating from said retractor portion whenboth said distractor portion and retractor portion together are insertedinto the operating site with the insertion force applied to saiddistractor portion.
 5. The distractor retractor assembly of claim 1,wherein said distractor rod enables a removal force to be applied to thedistractor head and thereby remove the distractor head from said keywayand an operating site.